High in strength and rigidity, engineering plastics such as polyamide resin and polybutylene terephthalate resin have been widely used in fields such as automobile parts, electric/electronic parts, and building materials. In some uses, they are required to have high impact resistance in addition to strength and rigidity, and in recent years, efforts have been made to develop materials based on polymer alloys.
Patent documents 1 and 2 disclose a highly impact resistant thermoplastic composition comprising a polyamide and an ionomer. The material, however, does not have rigidity and impact resistance in a sufficiently good balance.
Patent document 3 discloses a resin composition comprising a thermoplastic resin and a resin with a reactive functional group and having a high rigidity, high impact resistance and good appearance maintained even after being deformed. In this resin composition, one resin forms a continuous phase while the other forms a dispersal phase, and both the continuous phase and the dispersal phase contain fine particles of 300 nm or less. The composition, however, requires a high content of a resin with a reactive functional group to develop a high impact resistance, and the balance between its rigidity and impact resistance is not sufficiently good.
Patent document 4 discloses a thermoplastic resin composition comprising a thermoplastic resin and a resin with a reactive functional group and having a high heat resistance and high impact absorbability. In this thermoplastic resin composition, one resin forms a continuous phase while the other forms a dispersal phase, and the dispersal phase has a specified three dimensional structure. According to an experimental study by the present inventors, however, the composition fails to have rigidity and impact resistance in a sufficiently good balance if the content of the resin with a reactive functional group is less than 15%.
It is known that engineering plastics can be reinforced by adding various fillers. Patent document 5, for instance, discloses a polyamide resin composition that comprises a polyamide resin, polyolefin elastomer, and a reinforcement fiber and has a high impact resistance and less deteriorated mechanical characteristics such as rigidity. The material, however, fails to have impact resistance and rigidity in a sufficiently good balance.
Patent document 6 discloses a molding material, along with a production method thereof, that is produced by impregnating a continuous reinforcement fiber bundles with a thermoplastic polymer with a relatively low molecular weight and combining it with a high-molecular weight thermoplastic resin to form a composite structure. This technique can produce a long fiber reinforced thermoplastic resin that has a largely improved moldability and productivity and also has both a high impact resistance and rigidity. Nevertheless, its impact resistance and rigidity are not sufficiently high when used to produce cases for electronic instruments, electric/electronic parts, automobile parts, building materials, and sporting goods.
Patent document 7 discloses a thermoplastic elastomer composition comprising a thermoplastic resin containing a microgel of a homopolymer or a random copolymer. In this material, however, the microgel is formed before being mixed with a thermoplastic resin, and there is no description about the reactivity of the microgel with the thermoplastic resin, and they cannot develop both impact resistance and rigidity in a sufficiently good balance.
Patent document 8 discloses an epoxy composition comprising an epoxy resin and rubber particles having a core-shell structure. In producing this material, however, the rubber particles having a core-shell structure are formed before being mixed with the epoxy resin. There are no description about the reactivity of the epoxy resin and the rubber particles having a core-shell structure, and the balance between impact resistance and rigidity is not sufficiently good.
Patent document 9 discloses a method to produce an impact resistant polymer composition, in which a matrix polymer containing a dispersed rubber composition is melted and mixed with a second matrix polymer. This material, however, has to contain both a functionalized rubber and a non-functionalized rubber for the rubber composition to have an appropriate morphology, and it has been found that a sufficiently good balance between impact resistance and rigidity cannot be achieved without using a non-functionalized rubber.